The disclosed invention relates to bridges, and more particularly to a modified suspension-type bridge which comprises a continuous cable in which tension is developed by operation of turnbuckles or the like, instead of hanging weights.
Conventional Suspension Bridges which have weights hanging from a Tension Cable where it comes off a pulley or functional equivalent, are known. The weights are balance for the Bridge Deck Load supported by Tension Cables which attach from the tops of vertically projecting supports located substantially at the ends of the Bridge Deck. The Tension Cables project centrally from the tops of the vertically projecting supports and affix to said Bridge Deck. The Brooklyn Bridge, for instance, is such a Bridge which has huge weights so hanging therefrom.
Cable Stayed Bridges are also known, in which typically vertically projecting supports are placed at approximately one-quarter the length of the Bridge Deck, from each extend thereof. Tension Cables project both centrally and laterally from the tops of each of the Supports, with the portions of the Bridge Deck located Laterally on each side of the supports providing the equivalent of the weights in a Conventional Suspension Bridge.
It is also known to apply turnbuckles in bridge construction, wherein said turnbuckles are used to effect cable tension.
No known bridge, however, replaces weights in a conventional Suspension Bridge, with a continuous cable/turnbuckle combination which continuous cable is present under a Bridge Deck.
With the invention disclosed herein, a Search of Patents was conducted.
Perhaps the best art found is in a Patent to Minakami et al., No. 5,513,408. FIG. 7 therein shows a bridge with upper (24) and lower (25) cables. Said upper and lower cables however are not continuous around pulleys at their connection to element (3) therein, and there are no turnbuckles present to provide tension.
A Soviet Patent, No. SU 1408-009-A identifies an element termed a xe2x80x9cregulation devicexe2x80x9d (6) at an interconnection between upper (5) and lower (7) cables, however the presence of pulleys are not indicated.
U.S. Pat. No. 2,311,241 to Martin identifies hydraulic jacks (62) as means for tension development.
U.S. Pat. No. 511,605 to Frederick identifies eye-bolts in cable (K), which can be replaced by turnbuckles.
U.S. Pat. No. 2,842,786 to Digby-Smith identifies tension producing nuts (12) applied to cable (2).
Additional Patents turned-up are:
U.S. Pat. No. 4,535,498 to Webster;
U.S. Pat. No. 3,114,161 to Colombot;
Soviet Patent No. SU 1249-093-A.
Even in view of the known prior art, need remains for improved a modified cable stayed bridge.
The disclosed invention is a bridge system comprising, as viewed in side elevation:
an elongated lower support which comprises cable directing means, (eg. a pulley or functional equivalent at each end thereof;
a cantered right support;
a cantered left support;
a tension cable with a tension producing means (eg. a turnbuckle) therein; and
suspension cables. Said cantered right support is oriented at an angle upward and to the left and said left cantered support is oriented at an angle upward and to the right, lower ends each thereof being fixed upon and secured in a separate underlying right and left support abutments. The suspension cables are affixed to tops of said right and left supports and each is affixed centrally therebetween to said elongated lower support. The tension cable is affixed to the tops of said right and left supports and is strung through said pulleys or functional equivalents at the ends of said elongated lower support, and said tension cable is functionally continuous under said elongated lower support.
The disclosed invention can be more precisely described as a bridge system comprising right and left half-bridge systems, each said half section being as described above. Said right and left half-bridge systems are aligned one in front of the other as viewed in side elevation, but are offset from one another as viewed in frontal elevation, (eg. as viewed at an entry/exit to the bridge). Said right and left half-bridge systems are secured in relative position with respect to one another, via interconnection means and the elongated lower support.
The elongated lower support means is typically comprised of many sections.
It is also to be noted that the tension cable is affixed to the tops of the supports, and that said tension cable which passes over said pulleys can have a tension producing means, (eq. turnbuckle), included therewithin which when operated create tension therein.
A method of constructing a modified suspension bridge comprises the steps of:
a. providing right and left abutments separated by a distance;
b. mounting two right cantered supports, each, as viewed in side elevation, oriented at an angle upward and to the left, to said right abutment; and mounting two left cantered supports, each, as viewed in side elevation, oriented at an angle upward and to the right, to said left abutment; said two right and two left cantered supports being separated from one another as viewed in frontal elevation, and, as viewed in side elevation, said two right cantered supports being one in front of the other and said two left cantered supports being one in front of the other;
c. at the right or left abutment location mounting a right or left length of a lower support which comprises two cable directing means at the lateral end thereof, one of said cable directing means being substantially in-line with one right or left cantered support and the other of said cable directing means being substantially in-line with the other right or left cantered support near the associated abutment; and
at the left or right abutment location mounting a left or right length of a lower support, or functional equivalent, which comprises two cable directing means at the lateral end thereof, one of said cable directing means being substantially in-line with one left or right cantered support and the other of said cable directing means being substantially in-line with the other left or right cantered support near the associated abutment;
d. attaching a tension cable to the tops of said right and left cantered supports which are in front of the other right and left cantered supports and causing it to proceed through the respective cable directing means; and
attaching a tension cable to the tops of said right and left cantered supports which are behind the other right and left cantered supports and causing it to proceed through the respective cable directing means at the ends of the lengths of the lower supports at the right and left; and
e. placing additional lengths of lower support between the right and left lengths of lower supports; and
securing suspension cables between the tops of both said right and left cantered supports to said lower support centrally between both said right and left cantered supports.
It is noted that one of the xe2x80x9clengths of a lower support which comprises two cable directing means at one end thereofxe2x80x9d mounted in Step xe2x80x9ccxe2x80x9d can be other than a permanent xe2x80x9clength of a lower supportxe2x80x9d, and serve only to provide the xe2x80x9ctwo cable directing means at one end thereofxe2x80x9d. It is functionally the presence of the two cable directing means at each end of the Lower Support which is important.
It is noted that the method will typically involve providing tension producing devices (eg. turnbuckles), to produce tension in the tension cable, however an additional step, after production of tension thereby, can be to bypass and eliminate said tension producing device. The bypass can be effected via affixing lengths of tension cable around the tension producing device, and then optionally removing the tension producing device.
The disclosed invention will be better understood by reference to the Detailed Description in combination with the Drawings.
It is therefore a primary purpose and/or objective of the disclosed invention to teach a Modified Suspension Bridge which has a continuous Tension Cable (TC) in place of counter weights.